Estimation of bumblebee queen dispersal distances using sibship reconstruction method

Dispersal ability is a key determinant of the propensity of an organism to cope with habitat fragmentation and climate change. Here we quantify queen dispersal in two common bumblebee species in an arable landscape. Dispersal was measured by taking DNA samples from workers in the spring and summer, and from queens in the following spring, at 14 sites across a landscape. The queens captured in the spring must be full sisters of workers that were foraging in the previous year. A range of sibship reconstruction methods were compared using simulated data sets including or no genotyping errors. The program Colony gave the most accurate reconstruction and was used for our analysis of queen dispersal. Comparison of queen dispersion with worker foraging distances was used to take into account an expected low level of false identification of sister pairs which might otherwise lead to overestimates of dispersal. Our data show that Bombus pascuorum and B. lapidarius queens can disperse by at least 3 and 5 km, respectively. These estimates are consistent with inferences drawn from studies of population structuring in common and rare bumblebee species, and suggest that regular gene flow over several kilometres due to queen dispersal are likely to be sufficient to maintain genetic cohesion of ubiquitous species over large spatial scales whereas rare bumblebee species appear unable to regularly disperse over distances greater than 10 km. Our results have clear implications for conservation strategies for this important pollinator group, particularly when attempting to conserve fragmented populations.     

Cladistic review of generic taxonomic characters in Xyleborina (Coleoptera: Curculionidae: Scolytinae)

Abstract A cladistic analysis of morphological characters of the subtribe Xyleborina (Curculionidae, Scolytinae) is presented. An examination of individual characters revealed little phylogenetic information in many characters currently used for delimiting genera. Phylogenetically stable characters were used for the evaluation of the contemporary generic concept. The following genera have been recovered as monophyletic: Cnestus, Dryocoetoides, Eccoptopterus, Xylosandrus, Schedlia, Sampsonius and Taurodemus. The following genera have been found to be polyphyletic: Amasa, Ambrosiodmus, Arixyleborus, Coptoborus, Coptodryas, Cryptoxyleborus, Cyclorhipidion, Euwallacea, Leptoxyleborus, Taphrodasus, Theoborus, Webbia, Xyleborinus and Xyleborus. The analysis permitted the resurrection of four genera: Anisandrus, Microperus, Pseudowebbia and Streptocranus. A number of new combinations at specific level are given: Anisandrus cornutus (Schaufuss, 1891), A. dispar (Fabricius, 1792), A. eggersi (Beeson, 1930), A. improbus (Sampson, 1913), A. longidens (Eggers, 1930), A. maiche Stark, 1936, A. obesus (LeConte, 1868), A. sayi Hopkins, 1915, A. apicalis (Blandford, 1894), A. hirtus (Hagedorn, 1904), Microperus myristicae (Schedl, 1939), M. eucalypticus (Schedl, 1938), M. huangi (Browne, 1983), M. intermedius (Eggers, 1923), M. kadoyamaensis (Murayama, 1934), Pseudowebbia armifer (Schedl, 1942), P. seriata Browne, 1963, P. squamatilis (Schedl, 1955), P. trepanicauda (Eggers, 1923), P. curvatus (Browne, 1986), Streptocranus bicolor Browne, 1949, S. bicuspis (Eggers, 1940), S. capucinulus (Schedl, 1942), S. forficatus (Schedl, 1957), S. fragilis Browne, 1949, S. longicauda Browne, 1960, S. longispinis Browne, 1986, S. mirabilis Schedl, 1939, S. usagaricus (Eggers, 1922), S. sexdentatus (Eggers, 1940). The characters most useful for generic‐level taxonomy of Xyleborina were identified and their states refined and illustrated. An accompanying illustrated multiple‐entry electronic key for the updated xyleborine classification has been published on‐line at www.scolytid.msu.edu .     

Fungal community responses to precipitation

Understanding how fungal communities are affected by precipitation is an essential aspect of predicting soil functional responses to future climate change and the consequences of those responses for the soil carbon cycle. We tracked fungal abundance, fungal community composition, and soil carbon across 4 years in long‐term field manipulations of rainfall in northern California. Fungi responded directly to rainfall levels, with more abundant, diverse, and consistent communities predominating under drought conditions, and less abundant, less diverse, and more variable communities emerging during wetter periods and in rain‐addition treatments. Soil carbon storage itself did not vary with rainfall amendments, but increased decomposition rates foreshadow longer‐term losses of soil carbon under conditions of extended seasonal rainfall. The repeated recovery of fungal diversity and abundance during periodic drought events suggests that species with a wide range of environmental tolerances coexist in this community, consistent with a storage effect in soil fungi. Increased diversity during dry periods further suggests that drought stress moderates competition among fungal taxa. Based on the responses observed here, we suggest that there may be a relationship between the timescale at which soil microbial communities experience natural environmental fluctuations and their ability to respond to future environmental change.     

The Development and Evolution of the Turtle Body Plan: Inferring Intrinsic Aspects of the Evolutionary Process from Experimental Embryology

The body plan of turtles is unique among tetrapods in the presenceof the shell. The structure of the carapace involves a uniquerelationship between the axial and the appendicular skeletons.A common developmental mechanism, an epithelial-mesenchymalinteraction, has been identified in the early stages of carapacedevelopment by means of basic histological and immunofluorescencetechniques. By analogy to other structures initiated by epithelial-mesenchymalinteractions, it is hypothesized that carapace development isdependent on this interaction in the body wall. Surgical perturbationswere designed to test the causal connection between the epithelial-mesenchymalinteraction in the body wall and the unusual placement of theribs in turtles. By comparison to data available on body wallformation in avian embryos, these experiments also shed lighton the segregation of somitic and lateral plate cell populationsand the embryonic origin of the scapula in turtles. This study specifically addresses the ontogeny of a unique tetrapodbody plan. The ontogenetic information can be used to make inferencesabout the phytogeny of this body plan and how it could haveevolved from the more typical primitive tetrapod. On a moregeneral level this studyexplores the potential role of commondevelopmental mechanisms in the generation of evolutionary novelties,and the developmental incongruities between homologous skeletalelements in different groups of tetrapods.     

Evaluation of Attractants to Improve Trapping Success of Nutria on Louisiana Coastal Marsh

ABSTRACT Nutria (Myocastor coypus) are an important part of the Louisiana (USA) fur industry, but high densities of nutria cause extensive damage to coastal marsh ecosystems. Hence, there is a need to develop improved methods for targeted management of nutria. We screened 14 olfactory cues as potential lures for nutria, first in controlled settings and then in the field, to see if nutria capture rates using foothold traps would increase. In Y-maze trials, nutria most frequently selected olfactory cues of a synthetic formulation of nutria anal-gland secretion and nutria fur extract. We examined the 3 most selected attractants in Y-maze trials and female nutria urine under field conditions to compare trapping success over untreated traps. Capture probability was nearly 2.5 times greater for fur wash than control and 2 times greater for urine than control (relative risk = 2.43 and 2.01, respectively). The results suggest that use of semiochemicals and synthetic formulations of semiochemicals increased nutria trapping success. Development and use of effective synthetic semiochemicals could benefit resource managers nationwide who are responsible for reducing damage caused by this invasive herbivore.     

Lake responses to reduced nutrient loading – an analysis of contemporary long-term data from 35 case studies

1. This synthesis examines 35 long‐term (5–35 years, mean: 16 years) lake re‐oligotrophication studies. It covers lakes ranging from shallow (mean depth <5 m and/or polymictic) to deep (mean depth up to 177 m), oligotrophic to hypertrophic (summer mean total phosphorus concentration from 7.5 to 3500 μg L^?1 before loading reduction), subtropical to temperate (latitude: 28–65°), and lowland to upland (altitude: 0–481 m). Shallow north‐temperate lakes were most abundant. 2. Reduction of external total phosphorus (TP) loading resulted in lower in‐lake TP concentration, lower chlorophyll a (chl a) concentration and higher Secchi depth in most lakes. Internal loading delayed the recovery, but in most lakes a new equilibrium for TP was reached after 10–15 years, which was only marginally influenced by the hydraulic retention time of the lakes. With decreasing TP concentration, the concentration of soluble reactive phosphorus (SRP) also declined substantially. 3. Decreases (if any) in total nitrogen (TN) loading were lower than for TP in most lakes. As a result, the TN : TP ratio in lake water increased in 80% of the lakes. In lakes where the TN loading was reduced, the annual mean in‐lake TN concentration responded rapidly. Concentrations largely followed predictions derived from an empirical model developed earlier for Danish lakes, which includes external TN loading, hydraulic retention time and mean depth as explanatory variables. 4. Phytoplankton clearly responded to reduced nutrient loading, mainly reflecting declining TP concentrations. Declines in phytoplankton biomass were accompanied by shifts in community structure. In deep lakes, chrysophytes and dinophytes assumed greater importance at the expense of cyanobacteria. Diatoms, cryptophytes and chrysophytes became more dominant in shallow lakes, while no significant change was seen for cyanobacteria. 5. The observed declines in phytoplankton biomass and chl a may have been further augmented by enhanced zooplankton grazing, as indicated by increases in the zooplankton : phytoplankton biomass ratio and declines in the chl a : TP ratio at a summer mean TP concentration of <100–150 μg L^?1. This effect was strongest in shallow lakes. This implies potentially higher rates of zooplankton grazing and may be ascribed to the observed large changes in fish community structure and biomass with decreasing TP contribution. In 82% of the lakes for which data on fish are available, fish biomass declined with TP. The percentage of piscivores increased in 80% of those lakes and often a shift occurred towards dominance by fish species characteristic of less eutrophic waters. 6. Data on macrophytes were available only for a small subsample of lakes. In several of those lakes, abundance, coverage, plant volume inhabited or depth distribution of submerged macrophytes increased during oligotrophication, but in others no changes were observed despite greater water clarity. 7. Recovery of lakes after nutrient loading reduction may be confounded by concomitant environmental changes such as global warming. However, effects of global change are likely to run counter to reductions in nutrient loading rather than reinforcing re‐oligotrophication.